(with diagrams and calculations from well head down to injection). I am after the injection/reinjection temperature, an approximation or range at least and how this injection temperature range came to be. The temperature drops from heat exchange with binary fluids(recuperators and vaporizers) ,from double flashing and from condensation. I need that temperature for thermal pollution evaluation and silica deposition assessment from possible optimizations of a single flash cycled plant.
A binary cycle power plant is a type of geothermal power plant that allows cooler geothermal reservoirs to be used than is necessary for dry steam and flash steam plants.
injection temperature is taken at SSI = 1. this precludes silica deposition. if the operator can tolerate it, SS = 1.1.
Hi，Jan,
Check this paper: An integrated “Reservoir-Plant” strategy for a sustainable and efficient use of
geothermal resources (Energy 37, 2012, 299-310).
Firstly I have to mention that every reservoir has its own characteristic. There are many parameters controlling of the well head temperature (such as ambient temperature, NCG ratio, pressure etc.) so there is no unique answer for your question, if you do not have data for a specific reservoir. But of course it can be figured out for ideal conditions without considering entropy and NCG. In Binary system, injection temperature is controlled by vaporization point of the working fluid (such as pentane, butane etc.) at plant working pressure. As they are vaporizing at lower temperature than geothermal brine, you can cycle the brine until it reaches to working fluid vaporization point in theoretically. But the cooler brine will cause more scaling if there is a scaling problem. So knowing chemical composition of the brine to determining injection temperature is playing key role. In heat exchanger, brine transfers its heat to working fluid by conduction in flash system. Recuperator and preheater used to recover waste heat. In flash systems, steam of the brine which is a function of the pressure directly used for electricity generation. The pressure increases the vaporization point also increases. So you need more energy to vaporize brine at higher pressures. If you lower the pressure, the exceeding energy will yield vaporization of the brine and steam will be come out to lower the temperature. So in this system, if there is no binary extension, injection temperature will be at the value that allowed by plant outlet pressure which you can follow by steam table. You can get additional information from following publication.
Article Geothermal power plants: Evolution and performance assessments
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